Answer:
See explanation
Explanation:
When a beaker of ethanoic acid is placed in the refrigerator, its temperature drops and the vessel feels cool.
Now, when we mix ethanoic acid and sodium carbonate, an endothermic reaction occurs, fizzing is observed as carbon dioxide is given off and heat is lost to the surroundings causing the reaction vessel to feel cool to touch.
The difference between putting ethanoic acid in the refrigerator and adding sodium carbonate to the solution is that, in the former, no new substance is formed. The substance remains ethanoic acid when retrieved from the refrigerator. In the later case, new substances are formed. The substance is no more ethanoic acid because a chemical reaction has taken place.
The periodic table is arranged by the outermost electrons of the elements and this is the statement among the given statements that explains how the periodic table is arranged. The correct option among all the options that are given in the question is the second option or option "B".
The answer is (C) as the definitions states that atomic mass is the number of protons and neutrons.
Hope this helps :).
The area of the periodic table that has the most elements included within it is metals (option A).
<h3>What is periodic table?</h3>
Periodic table of elements is a tabular chart of the chemical elements according to their atomic numbers so that elements with similar properties are in the same group (column).
The periodic table encompasses chemical elements arranged horizontally and vertically. The periodic table is made up of groups and periods.
However, most of the elements on the periodic table are metals because virtually 93 elements are metals.
Therefore, the area of the periodic table that has the most elements included within it is metals.
Learn more about periodic table at: brainly.com/question/11155928
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Element Atomic Number Valency
Valency of Hydrogen 1 1
Valency of Helium 2 0
Valency of Lithium 3 1
Valency of Beryllium 4 2
Valency of Boron 5 3
Valency of Carbon 6 4
Valency of Nitrogen 7 3
Valency of Oxygen 8 2
Valency of Fluorine 9 1
Valency of Neon 10 0
Valency of Sodium (Na) 11 1
Valency of Magnesium (Mg) 12 2
Valency of Aluminium 13 3
Valency of Silicon 14 4
Valency of Phosphorus 15 3
Valency of Sulphur 16 2
Valency of Chlorine 17 1
Valency of Argon 18 0
Valency of Potassium (K) 19 1
Valency of Calcium 20 2
Valency of Scandium 21 3
Valency of Titanium 22 4
Valency of Vanadium 23 5,4
Valency of Chromium 24 2
Valency of Manganese 25 7, 4, 2
Valency of Iron (Fe) 26 2, 3
Valency of Cobalt 27 3, 2
Valency of Nickel 28 2
Valency of Copper (Cu) 29 2, 1
Valency of Zinc 30 2
